Control method of laundry machine

ABSTRACT

Control methods of a laundry machine are disclosed. One of them is a control method of a laundry machine comprising a water supplying step configured to drive the drum of the machine in scrub motion when water is supplied to the tub of the machine. Another control method of the laundry machine comprising a washing cycle with at least one water supplying step configured to drive the drum in a predetermined time period after water supply to the tub starts or after the water level reaches a predetermined value.

TECHNICAL FIELD

The present invention relates to a control method of a laundry machine.

BACKGROUND ART

In general, a laundry machine may include washing, rinsing and spinningcycles. However, the conventional laundry machine has problems.

DISCLOSURE OF INVENTION Technical Problem

Accordingly, the present invention is directed to a control method of alaundry machine.

Solution to Problem

To solve the problems, an object of the present invention is to providea control method of a laundry machine comprising a water supplying stepconfigured to drive a drum in a scrub motion when water is supplied to atub.

Advantageous Effects of Invention

The present invention has following advantageous effects.

According to the control method of the present invention describedabove, it is possible to provide a control having a high efficiencywashing cycle.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, illustrate embodiments of the disclosure andtogether with the description serve to explain the principle of thedisclosure.

In the drawings:

FIG. 1 is a sectional view of an exemplary laundry machine as embodiedand broadly described herein;

FIG. 2 is an exploded perspective view illustrating a laundry machineaccording to a second embodiment to which the spinning cycle controlmethod is applied;

FIG. 3 is a sectional view illustrating a connecting state of FIG. 2;

FIG. 4 illustrate various drum motions and laundry movement patterns asembodied and broadly described herein;

FIG. 5 is a graph illustrating a water temperature and drive of acirculation pump in a washing cycle;

FIGS. 6 and 7 are graphs illustrating a rpm change of a drum in aspinning cycle;

FIG. 8 is a graph showing a relation of mass vs. a natural frequency;

FIG. 9 is a graph illustrating vibration characteristics of the laundrymachine.

BEST MODE FOR CARRYING OUT THE INVENTION

As follows, a control method of a laundry machine according to thepresent invention will be described in reference to the accompanyingdrawings. Laundry machines according to various embodiments, to whichcontrol methods of the present invention can be applied, will bedescribed in corresponding drawings first and the control methods willbe described after that.

FIG. 1 is a diagram illustrating a laundry machine according to a firstembodiment of the present invention, to which control methods accordingto various embodiments can be applied.

In reference to FIG. 1, a laundry machine 100 according to a firstembodiment of the present invention includes a cabinet 10 configured todefine an exterior appearance thereof, a tub 20 provided in the cabinet10 to hold wash water therein and a rotatable drum 30 provided in thetub 20.

The cabinet 10 defines the exterior appearance of the laundry machine100 and configuration elements, which will be described later, may bemounted in the cabinet 10. A door 11 is coupled to a front plate of thecabinet 10 and a user opens the door 11 to load laundry into the cabinet10.

The tub 20 is provided in the cabinet 10 and it holds wash watertherein. The drum 30 may be rotatable in the tub 20 and it accommodateslaundry therein. In this case, a plurality of lifters 31 may be providedin the drum 30 and they lift and drop the laundry to implement washing.

The tub 20 is supported by a spring provided beyond the tub 20. A motor40 is mounted to a rear surface of the tub 20 and the motor 40 rotatesthe drum 30. When vibration is generated by the drum rotated by themotor 40, the tub 20 provided in the laundry machine according to thefirst embodiment is vibrated in communication with the drum. In case thedrum 30 is rotated, the vibration generated in the drum and the tub 20may be absorbed by a damper 60 located under the tub 20.

As shown in FIG. 1, the tub 20 and the drum 30 may be provided inparallel to a base plate of the cabinet 10. Alternatively, although notshown in the drawings, rear portions of the tub 20 and the drum 30 maybe oblique downward. This is because front portions of the tub 20 andthe drum 30 had better be obliquely upward in case the user loads thelaundry into the drum 30. A ball balancer 70 is provided in a frontsurface and/or a rear surface of the drum 30 to balance the vibration ofthe drum 30 in case the drum is rotated, especially, the drum is rotatedat a high speed such as a dry-spinning cycle. The ball balancer will bedescribed in detail later.

According to a laundry machine according to an embodiment, the tub maybe fixedly supported to the cabinet or it may be supplied to the cabinetby a flexible supporting structure such as a suspension unit which willbe described later. Also, the supporting of the tub may be between thesupporting of the suspension unit and the completely fixed supporting.

That is, the tub may be flexibly supported by the suspension unit whichwill be described later or it may be complete-fixedly supported to bemovable more rigidly. Although not shown in the drawings, the cabinetmay not be provided unlike embodiments which will be described later.For example, in case of a built-in type laundry machine, a predeterminedspace in which the built-in type laundry machine will be installed maybe formed by a wall structure and the like, instead of the cabinet. Inother words, the built-in type laundry machine may not include a cabinetconfigured to define an exterior appearance thereof independently.

FIG. 2 is an exploded perspective view partially illustrating a laundrymachine according to a second embodiment and FIG. 3 is a sectional viewillustrating an assembled state of the laundry machine shown in FIG. 2.

In reference to FIGS. 2 and 3, the laundry machine according to thisembodiment includes a tub 12 fixedly supported to a cabinet. The tub 12may include a tub front 100 configured to define a front part thereofand a tub rear 120 configured to define a rear part thereof. The tubfront 100 and the tub rear 120 are assembled to each other by screws anda predetermined space is formed in the assembled structure toaccommodate the drum. The tub rear 120 may include an opening formed ina rear surface thereof and an inner circumference of the rear surface ofthe tub rear 120 is connected with an outer circumference of a reargasket 250. An inner circumference of the rear gasket 250 is connectedwith a tub back 130. The tub back 130 includes a through-hole formed ina center thereof and a shaft passes the through-hole. The rear gasket250 may be made of flexible material not to transmit the vibration ofthe tub back 130 to the tub rear 120.

The tub rear 120 includes a rear surface 128. The rear surface 128 ofthe tub rear 120, the tub back 130 and the rear gasket 250 define a rearwall of the tub. The rear gasket 250 is sealingly connected with the tubback 130 and the tub rear 120 and it prevents wash water held in the tubfrom leaking out. The tub back 130 is vibrated together with the drumduring the rotation of the drum. Because of that, the tub back 130 isspaced apart a predetermined distance enough not to interfere with thetub rear 120. Since it is made of flexible material, the rear gasket 250allows the tub back 130 to relative-move without interfering with thetub rear 120. The rear gasket 250 may include a corrugation part 252extendible enough to allow such the relative movement of the tub back130.

A foreign-substance-preventing member 200 is connected with a frontportion of the tub front 100 to prevent foreign substances from comingbetween the tub and the drum. The foreign-substance-preventing member200 is made of flexible material and it is fixedly installed to the tubfront 100. The foreign-substance-preventing member 200 may be made ofidentical material to material used to make the rear gasket 250 and itwill be referenced to as front gasket for convenience sake.

The drum 32 includes a drum front 300, a drum center 320 and a drum back340. Ball balancers 310 and 330 are installed in front and rear portionsof the drum, respectively. The drum back 340 is connected with a spider350 and the spider 350 is connected with a shaft 351. The drum 32 isrotated in the tub by the rotational force transmitted via the shaft 351from a motor.

The shaft 351 is directly connected with a motor 170, passing throughthe tub back 130. Specifically, the shaft 351 is directly connected witha rotor 174 composing the motor 170. A bearing housing 400 is coupled toa rear surface of the tub back 130 and the bearing housing 400 islocated between the motor 170 and the tub back 130 to rotatably supportthe shaft 351.

A stator 172 is fixedly installed to the bearing housing 400 and therotor 174 is located around the stator 172. As mentioned above, therotor 174 is directly connected with the shaft 351. The motor 170 is anouter rotor type motor and it is directly connected with the shaft 351.

The bearing housing 400 is supported by a suspension unit with respectto a cabinet base 600 and the suspension unit 18 includes threeperpendicular supporting suspensions and oblique-supporting suspensionsconfigured to support the bearing housing obliquely in a forward andrearward direction.

The suspension unit 180 may include a first cylinder spring 520, asecond cylinder spring 510, a third cylinder spring 500, a firstcylinder damper 540 and a second cylinder damper 530.

The first cylinder spring 520 is provided between a first suspensionbracket 450 and the cabinet base 600 and the second cylinder spring 510is provided between a second suspension bracket 440 and the cabinet base600.

The third cylinder spring 500 is directly connected between the bearinghousing 400 and the cabinet base 600.

The first cylinder damper 540 is obliquely installed between the firstsuspension bracket 450 and a rear portion of the cabinet base. Thesecond cylinder damper 530 is obliquely installed between the secondsuspension bracket 440 and the rear portion of the cabinet base.

The cylinder springs 520, 510 and 500 of the suspension unit 180 may beconnected to the cabinet base 600 flexibly enough to allow the drum tomove in a forward-and-rearward direction and a rightward-and-leftwarddirection, not completely fixed to the cabinet base. That is, thecylinder springs 520, 510 and 500 elastically support the drum to allowthe drum to rotate vertically and horizontally with respect to theconnected point with the cabinet base.

The perpendicular ones of the suspensions suspend the vibration of thedrum elastically and the oblique ones dampen the vibration. That is, outof the vibration system configured of springs and damping means, theperpendicularly installed ones are employed as springs and the obliquelyinstalled ones are employed as damping means.

The tub front 100 and the tub rear 120 are fixedly secured to thecabinet 110 and the vibration of the drum 32 is suspendingly supportedby the suspension unit 180. Substantially, the structure of the tub 12and the drum 32 may be separate. Even when the drum 32 is vibrated, thetub 12 may not be vibrated structurally.

The bearing housing 400 and the suspension brackets are connected byfirst and second weights 431 and 430.

A water supply line 722 is provided in the cabinet 110 and the watersupply line 722 is connected with an external water supply source suchas a water tap. The control part on-off-controls a water supply valve720 to supply water to the tub 12 via the water supply line 722. An endof the water supply line 722 is connected with a front part of the tub12 or the front gasket 200, to supply the water to the inside of the tubfrom the front part. In case a detergent box 710 is provided along thewater supply line 722, the water may be supplied together withdetergent.

In the meanwhile, a circulation pump 730 may be provided below the tub12 and the circulation pump 730 circulates the water discharged from thetub 12 to re-supply it to the tub. In case the water is required to becirculated by the circulation pump 730 in the laundry machine accordingto the second embodiment, a vale 732 is adjusted and the circulationpump 730 is connected with a circulation line 744. An end of thecirculation line is connected with the front part of the tub or thefront gasket 200 to supply the water to the tub inside from the frontpart. In case the water is required to be drained from the tub 12, thecirculation pump 730 is connected with a drainage line 742 to drain thewater. Although not shown in the drawings, a circulation pump configuredto circulate water and a drainage pump configured to drain the water maybe provided separately. In this case, the circulation line and thedrainage line are connected with the circulation pump and the drainagepump, respectively.

The tub 12 and the drum 32 may be installed in parallel to or oblique tothe cabinet base 600 at a predetermined angle. In this case, rearportions of the tub 12 and the drum 32 may be oblique downward for theuser to load the laundry into the drum 32 more smoothly.

If the laundry 1 is accommodated in the drum 30 and 32 and the drum 30and 32 are rotated in the laundry machine according to the aboveembodiments, noise and vibration would be generated a lot according tothe location of the laundry 1. For example, when the drum 30 and 32 isrotated with the laundry not distributed in the drum 30 and 32 uniformly(hereinafter, ‘eccentric rotation’, severe vibration and noise mayoccur. Especially, when the drum 30 and 32 is rotated at a high speedduring the dry-spinning cycle, the vibration and the noise will be aproblem

As a result, the laundry machine may include a ball balancer 70, 310 and330 to prevent the vibration and noise generated by the eccentricrotation of the drum 30 and 32. The ball balancer 70, 310 and 330 may beprovided in a front portion or rear portion or each of the front andrear portions.

The ball balancer 70, 310 and 330 is mounted to the rotatable drum 30and 32 to reduce eccentricity. Because of that, the ball balancer 70,310 and 330 may have a center of mass which is movable changeably. Thatis, the ball balancer (70, 310 and 330) may include a ball 72, 312 and332 having a predetermined weight and a path in which the ball ismovable along a circumferential direction.

Specifically, the ball is rotated by a friction force generated when thedrum 30 and 32 is rotated. When the drum is rotated, the ball is notkept in the drum and it is rotated at a different speed from the drum.Here, the laundry generating the eccentricity is in close contact withan inner wall of the drum and it can be rotated at almost the same speedas the drum because of an enough friction force and the lift of theinner wall. As a result, the rotation speed of the laundry is differentfrom that of the ball. The rotation speed of the laundry is faster thanthat of the ball in an initial rotation stage of the drum having arelatively slow speed. Precisely, an angular velocity of the laundry isfaster than an angular velocity of the ball. Also, a phase differencebetween the ball and the laundry, that is, a phase difference withrespect to a rotation center of the drum may changes continuously.

If the rotation speed of the drum is getting faster, the ball will be inclose contact with an outer circumferential surface of the moving pathbecause of a centrifugal force. At the same time, the ball is aligned ata position at which the phase difference between the ball and thelaundry is approximately 90° to 180°. If the rotation speed of the drumis a predetermined value or more, the centrifugal force is gettinglarger enough the friction force between the circumferential surface andthe ball to be a predetermined value or more, such that the ball may berotated at the same speed as the drum. in this case, the ball is rotatedat the same speed as the drum, with maintaining the position at whichthe phase difference with the laundry is 90° to 180°, preferably,approximately 180°. In this specification, the case of the ball beingrotated at the predetermined position with respect to the drum will bereferenced to as ‘eccentricity corresponding position’ or‘ball-balanced’ for convenience sake.

As a result, when the load of the laundry is concentrated on apredetermined portion inside the drum 30 and 32, the ball provided inthe ball balancer 70, 310 and 330 is moved to an eccentricitycorresponding position to reduce the eccentricity.

In the meanwhile, the drum may be drivable in various ways in the abovelaundry machine. That is, a driving motion of the drum may be determinedproperly according to each of washing, rinsing and dry-spinning cycles,or the user may properly determine a driving motion of the drumaccording to characteristics of a selected course. As follows, variousdriving motions applicable to a control method according to the presentinvention will be described in detail.

FIG. 4 is a diagram illustrating various drum driving motions. FIG. 4 isa front view schematically illustrating the drum to shown the rotationof the drum. according to FIG. 4, the inside of the drum is divided intofour parts in a counter-clockwise direction and the four parts aredefined as first, second, third and fourth quadrants to explain thelocation of the laundry according to the rotation angle of the drum.

In reference to FIG. 4, the drum driving motions may be embodied bycombination of the rotation direction, rotation speed and rotation angleof the drum. Also, the laundry located in the drum inside may have adifferent falling direction, falling point and shock when fallingbecause of the drum driving motions. By extension, it may have differentmovement of the laundry inside the drum. The various drum drivingmotions may be embodied by controlling the motor configured to rotatethe drum.

In the meanwhile, when the drum is rotated, the laundry is lifted by thelift (31, see FIG. 1 and 132, see FIG. 3) provided in the innercircumferential surface of the drum. Because of that, the rotationspeed, the rotation direction and the rotation angle of the drum arecontrolled and the shock applied to the laundry may be variedaccordingly. That is, a mechanical force applied to the laundry such asthe friction generated between laundry items, the friction generatedbetween the laundry and the water and the dropping shock of the laundrymay be varied and a degree of striking or scrubbing for the laundry maybe varied accordingly. In addition, the rotation speed, rotationdirection and rotation angle of the drum may be controlled and a degreeof laundry distribution or turn-over inside the drum may be variedaccordingly.

As a result, the control method of the laundry machine can providevarious drum driving motions and the drum driving motions are variedaccording to each of the cycles and a specific step composing the cycle,such that an optimal mechanical force may be used to treat the laundry.Because of that, washing efficiency of the laundry may be improved andthe time required by the optimal drum driving motion may be reduced.

In the meanwhile, the motor may be classified into a direct typeconnected with the shaft of the drum directly and an indirect typeconfigured to transmit a rotation force to the drum via a pulley and thelike. To embody the various drum driving motions, the motor 170 may bethe direct type connected with the drum directly. In case of therotation direction and torque of the motor, time delay or backlash maybe prevented and the motion of the motor may be transmitted to the drumspontaneously in the direct type.

The drum driving motions are configured of a rolling motion, tumblingmotion, step motion, swing motion, scrub motion and the like. Asfollows, each of the motions will be described in detail.

FIG. 4( a) is a diagram illustrating the rolling motion and each of FIG.4 shows a rotation direction and rotation angle of the drum and themovement of the laundry inside the drum, to explain each of the motions.

In reference to FIG. 4( a), in the rolling motion, the motor 40 and 170continuously rotates the drum 30 and 32 in a predetermined direction andthe laundry located on the inner circumferential surface of the drumrotating along the rotation direction of the drum is dropped to thelowest point of the drum from the position at an angle of approximatelyless than 90°.

That is, once the motor 40 and 170 rotates the drum at approximately 35RPM to 45 RPM, the laundry located in the lowest point of the drum 30and 32 is lifted to a predetermined height along the rotation directionof the drum 30 and 32 and then it rolling-moves to the lowest point ofthe drum from the position of less than 90° with respect to the lowestpoint of the drum. In case the drum is rotated in a clockwise direction,the laundry is rolling in the third quadrant of the drum continuously.The laundry is washed by the friction with the water and the frictiontherewith and the friction with the inner circumferential surface of thedrum in the rolling motion. The rolling motion enables the turn-over ofthe laundry implemented enough to generate an effect of softscrubbing-like washing.

In the meanwhile, the drum RPM of the drum driving motion is determinedby the relation with the centrifugal force, in case the drum is rotated.That is, the larger the drum RPM is, the larger centrifugal force isgenerated in the laundry inside the drum. If the centrifugal force islarger than the gravity, the laundry will be attached to the innercircumferential surface of the drum. If the centrifugal force is smallerthan the gravity, the laundry may be dropped to the bottom surface ofthe drum. As a result, the movement of the laundry inside the drum maybe varied by the relative size between the centrifugal force and thegravity. When the drum RPM is determined, the rotation force of the drumand the friction between the drum and the laundry may have to be putinto consideration.

The drum RPM is determined for the centrifugal force to be smaller thanthe gravity in the above rolling motion. That is, the laundry isrolling-dropped along the rotation of the drum in the rolling motion andthe centrifugal force has to be smaller than the gravity accordingly.

FIG. 4( b) is a diagram illustrating the tumbling motion.

In reference to FIG. 4( b), in the tumbling motion, the motor 40 and 170continuously rotates the drum 30 and 32 in a predetermined direction andthe laundry located on the inner circumferential surface of the drum isdropped to the lowest point of the drum from the position ofapproximately 90° to 110° with respect to the rotation direction of thedrum.

In the tumbling motion, only if the drum is controlled to be rotated ata proper RPM in a predetermined direction, the mechanical force isgenerated between the laundry and the drum. Because of that, thetumbling motion is typically used in the washing and the rinsing.

That is, the laundry loaded into the drum 30 and 32 is located in thelowest point of the drum 30 and 32 before the motor 40 and 170 isdriven. When the motor 40 and 170 provides a torque to the drum 30 and32, the drum 30 and 32 is rotated and the lifter 132 provided in theinner circumferential surface of the drum lifts the laundry to apredetermined height from the lowest point of the drum. if the motor 40and 170 rotates the drum 30 and 32 approximately at 46 RPM to 50 RPM,the laundry will be dropped to the lowest point of the drum from theposition of approximately 90° to 110° with respect to the rotationdirection of the drum. in the tumbling motion, the drum RPM isdetermined for a centrifugal force generated in the tumbling motion tobe larger than the centrifugal force generated, in case the drum isrotated, and to be smaller than the gravity.

If the drum is rotated in the clockwise direction in the tumblingmotion, the laundry is lifted to the second quadrant from the lowestpoint of the drum and then it is dropped to the lowest point of thedrum. As a result, the tumbling motion enables the laundry to be washedby the shock generated by the friction with the water and the droppingshock. In the tumbling motion, a larger mechanical force larger than themechanical force of the rolling motion may be used to implement washingand rinsing. Also, the tumbling motion is a motion in which the laundryis dropped inside the drum and it is effective in separating entangledlaundry and distributing the laundry uniformly.

FIG. 4( c) is a diagram illustrating the step motion.

In reference to FIG. 4( c), in the step motion, the motor 40 and 70rotates the drum 30 and 32 in a predetermined direction and the laundrylocated in the inner circumferential surface of the drum is controlledto be dropped to the lowest point of the drum from the highest point ofapproximately 180° with respect to the rotation direction of the drum.

Once the motor 40 and 170 rotates the drum 30 and 32 approximately at 60RPM to 77 RPM or more, the laundry may be rotated by the centrifugalforce until reaching the highest point of the drum, without beingdropped. In the step motion, in case the laundry reaches near thehighest point, the sudden brake is applied on the drum to maximize theshock applied to the laundry.

After rotating the drum 30 and 32 at a predetermined speed withoutdropping the laundry (approximately 60 RPM to 70 RPM or more) until thelaundry reaches the highest point of the drum by using the centrifugalforce, the motor 40 and 170 is controlled to supply a reverse torque tothe drum 30 and 32 when the laundry is located near the highest point ofthe drum (180° with respect to the rotation direction of the drum). Thelaundry is lifted from the lowest point of the drum along the rotationdirection of the drum. After that, when the drum is stopped momentarilyby the reverse torque of the motor, the laundry is dropped from thehighest point to the lowest point of the drum 30 and 32. As a result,the step motion enables the laundry to be washed by the shock generatedwhile the laundry is dropped at the maximum height. A mechanical forcegenerated in this step motion is larger than the mechanical forcegenerated in the rolling motion or tumbling motion mentioned above.

In case the sudden brake is applied like in the step motion, the motor40 and 170 may be reversing-phase-braked. The reversing-phase brake is abraking type of a motor by using a torque generated in a reversedirection with respect to a rotation direction of the motor. A phase ofa current supplied to the motor may be reversed to generate a reversetorque and the reversing-phase brake enables the sudden brake to beapplied to the motor. As a result, the reversing-phase brake is the mostproper brake system to the step motion configured to apply the strongshock to the laundry.

According to FIG. 4( c), in the step motion, after moved to the highestpoint from the lowest point of the drum via the third and secondquadrant sequentially in case the drum is rotated, the laundry isdropped to the lowest point out of the inner circumferential surface ofthe drum. As the dropping distance inside the drum is the largest in thestep motion, a mechanical force may be applied to a small amount of thelaundry.

Hence, the motor 40 and 170 re-applies a torque to the drum 30 and 32,the motor lifts the laundry located at the lowest point of the drum tothe highest point along the same rotation direction. That is, when thelaundry reaches the highest point after applying the torque to rotatethe drum in the clockwise direction, the torque is applied to rotate thedrum in the counter-clockwise direction and the drum is stoppedsuddenly. After that, a torque is applied to the drum to re-rotate inthe clockwise direction and the step motion is embodied. As a result,the step motion is a motion used to wash the laundry by using thefriction between the water drawn via the through hole (134, see FIG. 3)formed in the drum and the laundry and using the shock generated by thedropping the laundry when the laundry reaches the highest point of thedrum.

FIG. 4( d) is a diagram illustrating the swing motion.

In reference to FIG. 4( d), in the swing motion, the motor 40 and 170rotates the drum 30 and 32 in clockwise and counter-clockwise directionsalternatively and the laundry is dropped at approximately the 90° to130° position with respect to the rotation direction of the drum.

That is, once the motor 40 and 170 rotates the drum 30 and 32 atapproximately 40 RPM in the counter-clockwise direction, the laundrylocated at the lowest point of the drum 30 and 32 is lifted apredetermined height in the counter-clockwise direction. after thelaundry passes the 90° position with respect to the counter-clockwisedirection of the drum, the motor stops the rotation of the drum for thelaundry to be dropped to the lowest point of the drum from the 90° to130° position with respect to the counter-clockwise direction of thedrum.

Hence, the motor 40 and 170 rotates the drum 30 and 32 at approximately40 RPM in the clockwise direction to lift the laundry a predeterminedheight in the clockwise direction along the rotation direction of thedrum. After the laundry passes the 90° position with respect to thecounter-clockwise direction of the drum, the motor stops the rotation ofthe drum and the laundry is dropped to the lowest point of the drum fromthe 90° to 130° position with respect to the clockwise direction of thedrum.

That is, the swing motion is a motion in which the rotation and stopwith respect to the predetermined direction and the rotation and stopwith respect to the reverse direction may be repeated. The laundrylifted to a part of the second quadrant from the third quadrant of thedrum is dropped softly and it is re-lifted a part of the first quadrantfrom the fourth quadrant of the drum to be dropped softly repeatedly. Asa result, the laundry may be moved in a shape of a sided-‘8’ over thethird and fourth quadrants of the drum in the swing motion.

At this time, the motor 40 and 170 may use rheostatic braking. Accordingto the rheostatic braking, in case a current applied to a motor is off,the motor is employed as generator because of rotation inertia. In casethe current applied to the motor is off, a direction of the currentflowing in a coil of the motor will be changed into a reverse directionof the current before the power off and a force (Fleming's right handrule) is applied along a direction which interferes with the rotation ofthe motor, to put the motor on the brake. Different from thereversing-phase braking, the rheostatic braking may not put the motor onthe sudden brake but it may make the rotation direction of the drumchanged softly. As a result, the swing motion adapts the rheostaticbraking and the load put on the motor 40 and 170 may be reduced as muchas possible. Moreover, mechanical abrasion of the motor 40 and 170 maybe minimized and the shock applied to the laundry may be adjustedsimultaneously.

FIG. 4( e) is a diagram illustrating the scrub motion,

In reference to FIG. (e), in the scrub motion, the motor 40 and 170rotates the drum 30 and 32 in both of the clockwise andcounter-clockwise directions alternatively and the reversing-phasebraking is applied to the drum such that the laundry may be dropped fromthe 130° to 160° position with respect to the rotation direction of thedrum.

That is, once the motor 40 and 170 rotates the drum 30 and 32 atapproximately 60 RPM in the counter-clockwise direction, the laundrylocated in the lowest point of the drum 30 and 32 is lifted apredetermined height in the counter-clockwise direction. after thelaundry passes an approximately 90° position with respect to thecounter-clockwise direction of the drum, the motor provides the drum areverse torque to stop the drum temporarily. If then, the laundrylocated on the inner circumferential surface of the drum will be droppedrapidly.

Hence, the motor 40 and 170 rotates the drum at approximately 60 RPM inthe clockwise direction to lift the dropped laundry a predeterminedheight in the clockwise direction. after the laundry passes the 90°position with respect to the counter-clockwise direction of the drum,the motor 40 and 170 applies the reverse torque to the drum 30 and 32and the rotation of the drum is stopped temporarily. As a result, thelaundry located on the inner circumferential surface of the drum isdropped to the lowest point of the drum from the approximately 130° to160° position with respect to the clockwise direction of the drum.

As a result, the laundry may be dropped rapidly from the predeterminedheight to be washed in the scrub motion. Here, the motor 40 and 170 maybe reversing-phase-braked to stop the drum.

In the scrub motion, the rotation direction of the drum is changedrapidly and the laundry may not be out of the inner circumferentialsurface of the drum largely. Because of that, an effect ofstrong-scrubbing-like washing may be achieved in the scrub motion. Inthe scrub motion, it is repeated that the laundry moved to a part of thesecond quadrant via the third quadrant is dropped rapidly to bere-dropped after re-moved to a part of the first quadrant via the fourthquadrant. As a result, in the scrub motion, the lifted laundry isdropped along the inner circumferential surface of the drum repeatedly.

FIG. 4( f) is a diagram illustrating the filtration motion. In Thefiltration motion, the motor 40 and 170 rotates the drum 30 and 32 forthe laundry not to be dropped from the inner circumferential surface ofthe drum and the water is sprayed into the drum.

That is, in the filtration motion, while the laundry after spread isrotated in close contact with the inner circumferential surface of thedrum, the water is sprayed into the drum. The water is discharged out ofthe tub 120 from the laundry and the through hole 131 of the drum by thecentrifugal force. Since the filtration motion widens a surface area ofthe laundry and it enables the water to pass through the laundry, thewash water may be enabled to pass through the laundry and the wash watermay be supplied to the laundry uniformly.

FIG. 4( g) is a diagram illustrating the squeeze motion. In the squeezemotion, the motor 40 and 170 rotates the drum 30 and 32 for the laundrynot to be dropped from the inner circumferential surface of the drum bythe centrifugal force and after that, the motor lowers the rotationspeed of the drum 30 and 32 to separate the laundry from the innercircumferential surface of the drum. This process is repeated and thewater is sprayed into the drum during the rotation of the drum.

That is, the drum is rotated at the speed enough not to drop the laundryfrom the inner circumferential surface of the drum continuously in thefiltration motion. In contrast, the rotation speed of the drum ischanged to repeat the process of closely contacting the laundry in andseparating the laundry from the inner circumferential surface.

The process of the water spraying into the drum 30 and 32 in thefiltration motion and the squeeze motion may be implemented by using acirculation path and a pump although not shown in FIG. 1. The pump is incommunication with the lower surface of the tub 120 and it presses thewash water. An end of the circulation path is connected with the pumpand the water is sprayed from the upper portion of the drum into thedrum via the other end of the circulation path.

The circulation path and the pump mentioned above are required elementsin case of spraying the water held in the tub and the present inventionmay not exclude a case of spraying the water via a path connected withan external water supply source located outside of the cabinet.

In the meanwhile, FIG. 5 is a diagram illustrating the step motion morespecifically. Once the motor 40 and 170 applies the torque to the drum30 and 32 in the predetermined direction, the drum is rotated in thepredetermined direction and the laundry is lifted in the state of theclose contact with the inner circumferential surface of the drum. Atthis time, the drum may be rotated at approximately 60 RPm or more tolift the laundry in close contact with the inner circumferential surfaceof the drum. Here, the rotation speed of the drum is determined by therelation with an inner diameter of the drum and the determined rotationspeed may have the centrifugal force larger than the gravity.

Just before the laundry reaches the highest point of the drum, passingthe 90° position with respect of the rotation direction of the drum 30and 32, the motor 40 and 170 is reversing-phase-braked to stop therotation of the drum temporarily. The timing point of thereversing-phase-braking with respect to the motor 40 and 170 is closelyrelated to the location of the laundry inside the drum. Because of that,a device used to determine or expect the location of the laundry may beprovided and a sensing device including a Hall Effect sensor configuredto determine a rotation angle of a rotor may be one of examples.

The control part may determine a rotation direction as well as therotation angle of the rotor by using the hall sensor. This technicalfeature is well-known knowledge to anyone skilled in the art anddetailed description thereof will be omitted accordingly.

The control part may determine the rotation angle of the drum by usingthe sensing device and it controls the motor 40 and 170 to bereversing-phase-braked before the drum has a rotation angle of 180°.Here, the reversing-phase-braking means that a reverse current isapplied to rotate the drum in a reverse direction. For example, after acurrent is applied to the motor to rotate the drum in a clockwisedirection, a reverse current is rapidly applied to rotate the drum in aclockwise direction.

As a result, the drum rotated in the clockwise direction is stopped in amoment and the rotation angle at this time is substantially 180° to dropthe laundry to the lowest point from the highest point of the drum.After that, the current is continuously applied to rotate the drum inthe clockwise direction.

FIG. 5 shows that the drum is rotated in the clockwise direction. Here,while the drum is rotated in the counter-clockwise direction, the stepmotion may be implemented. Here, the step motion generates a lot of loadto the motor 40 and 170 and a net acting ratio of the step motion may bereduced.

The net acting ratio is a ratio of a motor driving time to a totaledvalue of the driving time and the stopping time of the motor 40 and 170.If the net acting ratio is ‘1’ it means that the motor is driven withouta stopping time. The step motion may be implemented at approximately 70%of the net acting ratio, considering the load of the motor. For example,the motor may be stopped for 4 seconds after driving for 10 seconds.

FIG. 6 is a diagram illustrating the scrub motion more specifically.Once the motor 40 and 170 applies the torque to the drum 30 and 32, thelaundry inside the drum is rotated in the clockwise direction. Here, themotor 40 and 170 may be controlled to rotate the drum 30 and 32 atapproximately 60 RPM or more to rotate the laundry in close contact withthe inner circumferential surface of the drum. After that, when thelaundry passes the 90° position with respect to the rotation directionof the drum, the motor 40 and 170 is reversed-phase-braked and thelaundry in close contact with the inner circumferential surface of thedrum is dropped to the lowest point of the drum accordingly.

When the laundry is dropped to the lowest point, the motor 40 and 170applies the torque to the drum to rotate the drum in thecounter-clockwise direction. As a result, the laundry is rotated in thecounter-clockwise direction, in close contact with the innercircumferential surface of the drum. When the laundry is located betweenthe 90° position with respect to the counter-clockwise direction and thehighest point of the drum from the lowest point, the motor isreversing-phase-braked and the laundry in close contact with the innercircumferential surface of the drum is dropped to the lowest point ofthe drum.

The scrub motion described above generates a lot of load applied to themotor 40 and 170, like the step motion. As a result, a net acting ratioof the scrub motion may be reduced. For example, the scrub motion isimplemented for 10 seconds and after that, it is stopped for 4 secondsand this process is repeated for the net acting ratio to be 70%.

Although not shown in the drawings, the braking type of the motor in thescrub motion is changed into the rheostatic braking in the swing motion.The timing point of the rheostatic braking is changed into the momentwhen the laundry reaches the 90° position with respect to the rotationdirection of the drum, and the detailed description of the swing motionwill be omitted accordingly.

FIG. 7 is a graph illustrating comparison of washing ability and avibration level of each motion shown in FIG. 4. A horizontal axispresents the washing ability and it is easier to separate contaminantscontained in the laundry as moving to the left. A vertical axis presentsthe vibration or noise level and the vibration level is higher as movingupward, with the washing time for the same laundry being reduced.

The step motion and the scrub motion are proper to washing coursesimplemented to reduce the washing time when the laundry has severecontaminant. The step motion and the scrub motion have a highvibration/noise level and they are not proper to washing coursesimplemented to wash sensitive fabric and to minimize noise andvibration.

The rolling motion has a good washing ability and a low vibration level,with minimized laundry damage and low motor load. As a result, therolling motion may be proper to all of the washing courses, especially,to detergent dissolution in an initial washing stage and to wet thelaundry.

The tumbling motion has a lower washing ability than the scrub motionand a middle vibration level in comparison to the scrub motion and therolling motion. The rolling motion has the lower vibration level but ithas a longer washing time than the tumbling motion. Because of that, thetumbling motion may be applicable to all of the washing courses and itis proper to a washing course required to distribute the laundryuniformly.

The squeeze motion has a similar washing ability to the tumbling motionand a higher vibration level than the tumbling motion. The squeezemotion repeats the process of closely contacting the laundry in andseparating the laundry from the inner circumferential surface of thedrum and in this process, the wash water is discharged outside of thedrum after passing the laundry. As a result, the squeeze motion isproper to the rinsing.

The filtration motion has a lower washing ability than the squeezemotion and a similar noise level to the rolling motion. In thefiltration motion, the water passes the laundry and discharged out ofthe drum, with the laundry in close contact with the innercircumferential surface of the drum. As a result, the filtration motionis proper to a course which requires wetting of the laundry.

The swing motion has the lowest vibration level and washing ability andit is proper to a low noise and low vibration washing course and to acourse for washing sensitive clothes.

As mentioned above, each drum driving motion has advantages anddisadvantages and it is preferable that those various drum drivingmotions are used properly. Each drum driving motion may have advantagesand disadvantages in the relation with the laundry amount. Even in caseof the same course and cycle, the various drum driving motions may beused properly with respect to the relation with the laundry amount.

As follows, a control method of the laundry machine including the drumdriving motions described above will be described. The laundry machinetypically includes washing, rinsing and dry-spinning cycles and thosecycles will be described from now on. Here, the washing cycle is a partof various courses or it may be implemented independently.

The washing cycle may include a water supplying step configured tosupply water and detergent to the tub 12 and 20 or the drum 30 and 32 todissolve the detergent in the water. That is, the water and thedetergent are mixedly supplied to wash the laundry. In addition, thewashing cycle may include a main-washing step configured to drive thedrum to wash the laundry. Here, the water supplying step may be apreparing step for the main washing step. As a result, it is preferableto improve efficiency of the water supplying step to improve efficiencyof the washing cycle (including washing efficiency and time-reducingefficiency).

The washing cycle may include a laundry wetting step and/or heating stepimplemented between the water supplying step and the main washing step.The control method which will be described is relating to the watersupplying step of the washing cycle and it will be described in detail.

The control part supplies wash water to the tub 12 and 20 in the watersupplying step. Specifically, the control part opens the water supplyvalve 720 and supplies the water to the tub 12, with the water passingthe water supply line 722 and the detergent box 710.

Since the detergent is supplied together with the water in the watersupplying step, detergent dissolution may be completely implementedduring the water supply step to improve the efficiency of the washingcycle. As a result, in the water supplying step, a predetermined processmay be implemented to accelerate the detergent dissolution in the water.If the water contacts with the laundry partially during the watersupplying, the water fails to wet the laundry uniformly and theefficiency of the washing cycle may deteriorate. Although the laundrywetting step is provided in the washing cycle, the water supplying stepmay include a process of making the laundry wet uniformly by the water.As follows, various embodiments of the detergent dissolutionaccelerating process and the uniformly wetting laundry process will bedescribed.

First of all, to accelerate the detergent dissolution, a motion (drumdriving motion) of moving the laundry inside the drum may apply a strongmechanical force to the water and the laundry. As a result, the stepmotion is preferable in the water supplying step to accelerate thedetergent dissolution, because the laundry lifted along the rotatingdrum is dropped out of the inner circumferential surface of the drum bythe braking of the drum and because this is repeated in the step motion.Of course, the scrub motion in which the laundry lifted along therotating drum is repeatedly dropped and lifted by the braking andreverse-rotating of the drum may be implemented in the water supplyingstep. In the step motion and the scrub motion, the drum after rotated isstopped rapidly and the moving direction of the laundry is changedrapidly. As a result, they may be motions capable of applying a strongshock to the laundry and the water, such that the strong mechanicalforce may be provided in an initial stage of the water supplying stepand that the detergent dissolution may be accelerated, only to improvethe efficiency of the washing cycle.

The detergent dissolution may be accelerated by repeating the sequentialcombination of the step and scrub motions. In this case, different typesof drum driving motions are combined and the laundry movement type andthe water flow type may be diversified. As a result, the efficiency ofthe washing cycle may be improved more.

As mentioned above, the water supplying step is a preparing step of themain washing step. Because of that, the detergent dissolution and thelaundry wetting have to be implemented quickly and completely in thewater supplying step and they may be implemented regardless of theamount of the laundry. However, considering the limited capacity of thedrum, the limited water able to be supplied to the drum, the drumdriving motion of the water supplying step may be controlled differentlyaccording to the laundry amount. This is because the drum driving motioncapable of achieving the maximum effect of the detergent dissolution andlaundry wetting may be differentiated according to the laundry amount.

A laundry amount determining step configured to determine the amount ofthe laundry accommodated in the drum may be implemented before the watersupplying step. The drum driving motion in the water supplying step maybe controlled differently according to the result of the laundry amountdetermining step.

Such the laundry amount determining may be implemented by measuring thecurrent required to rotate the drum. For example, the currents requiredto implement the tumble motion may be measured. In case the drum isrotated, the current value applied by the control part to implement thetumble motion may be differentiated according to the laundry amount andthe laundry amount may be determined.

If the laundry amount determined in the laundry amount determining stepis a preset laundry amount level or more, the process for the detergentdissolution may be controlled not to be implemented. That is, theprocess configured to accelerate the detergent dissolution may becontrolled to be implemented, if the laundry amount is the preset levelof less. This is because the drum driving motion capable of supplyingthe strong mechanical force is more effective in case the laundry amountis small and because the small amount of the laundry can be wet by thewater sufficiently. That is, the small amount of the laundry means thata surface area of the laundry required to contact with the water issmall and that the detergent dissolution and laundry wetting can beimplemented by the mechanical force used to turn over the laundry in ashort time. As a result, the effect of the main washing may be achievedpartially by the step motion or scrub motion and an effect of thereduced time required to implement the main washing may be expected.

In contrast, in case of the large amount of the laundry, the mechanicalforce may not be enough and the laundry may not contact with the waterenough. When the laundry is crumbled, the water fails to be supplied toitems inside the crumble laundry enough.

As a result, if the laundry amount is a preset level or more, theprocess of detergent dissolution acceleration is omitted and the laundrywetting step may start. When the laundry amount is a preset level ormore, it is more preferable to accelerate the detergent dissolution thatthe laundry contacts with the water enough. For that, a circulating stepconfigured to circulating the water held in the tub to re-supply it tothe drum may be implemented in the water supplying step.

According to the laundry machine according to the second embodimentdescribed above, the tub 12 is directly fixed to the cabinet 110 and thedrum 32 is provided in the tub 12. Since only the drum 32 is rotated inthe laundry machine according to the second embodiment, with the tub 12fixedly installed, it is important to prevent the contact between thedrum 32 and the tub 12 during the rotation of the drum. As a result, thedistance between the tub 12 and the drum may be formed larger in thelaundry machine than in the conventional laundry machine.

If the distance between the tub 12 and the drum 32 is widened, thelaundry inside the drum 32 may not be wet enough during the water supplyto the tub. To enable the laundry to be wet enough when the water issupplied, the laundry machine according to the second embodimentoperates the circulation pump 730 and water held in the tub may becirculated. For example, the circulation pump 730 may be drivencontinuously or at a predetermined interval, with the water supply valvebeing open.

According to the laundry machine of the second embodiment, the drum 32is connected with the tub back 30. The tub back 130 is supported by thesuspension unit 180 via the bearing housing 400, not by the tub 12. as aresult, compared with the drum 30 supported by the tub back 130 directlyconnected with the tub 12 in the laundry machine according to the firstembodiment, the drum 32 provided in the laundry machine according to thesecond embodiment, especially, the front part of the drum 32 has a largedegree of freedom.

In case the water is supplied to the tub 12, the water supply line 722and the circulation line 744 supply the water in the front portion ofthe tub 12 and the laundry located in the front portion of the drum maybe wet first. Because of that, the load applied to the front portion ofthe drum 32 is larger than the load applied to the rear portion and thefront portion of the drum 32 may go downward. If the front portion ofthe drum goes downward, the noise and vibration generated during therotation of the drum would be increased and rather than that, it wouldcontact with an inner surface of the tub 12. Because of that, it isrequired during the water supply in the laundry machine according to thesecond embodiment to wet the laundry located in both of the front andrear portions of the drum 32 uniformly.

As follows, a control method of wetting the laundry located in both ofthe front and rear portions of the drum uniformly according toembodiments of the present invention will be described, when the watersupply is implemented in the laundry machine according to the secondembodiment of the present invention.

In case the water is supplied in the water supplying step according tothe control method of the first embodiment, the circulation pump 730 isdriven to circulate the water and the drum 32 is driven simultaneously.When the drum 32 is driven, the control part controls the drum 32 to bedriven according to the scrub motion of the drum driving motionsdescribed above.

The distance between the drum 32 and the tub 12 in the laundry machineaccording to the second embodiment is larger than the distance betweenthem in the conventional laundry machine. Because of that, when thetumbling motion is applied to the drum 32 during the water supply likein the conventional laundry machine, the laundry located in the rearportion of the drum fails to be wet enough. That is, as the gap betweenthe drum 32 and the tub 12 is larger than the gap formed in theconventional laundry machine, the water located between the drum and thetub will not be lifted by the rotation of the drum, not to wet thelaundry located in the rear portion of the drum.

As a result, when the water supplying step is implemented according tothis control method, the scrub motion is implemented instead of thetumbling motion. As mentioned above, the scrub motion rotates the drumat the higher RPM than the tumbling motion and the water located betweenthe drum 32 and the tub 12 is lifted by the rotation of the drum 32, tofall onto the laundry.

Especially, the rear portions of the drum 32 and the tub 12 areobliquely structured in the laundry machine according to the secondembodiment. Because of that, the scrub motion enables the water locatedin the rear portion of the tub 12 to be supplied to the top of thelaundry smoothly. Also, the scrub motion rapidly changes the rotationdirection of the drum 32 in the clockwise direction andcounter-clockwise direction. Because of that, vortex is generated in thewash water by the rapid reversing of the rotation applied to the drumsuch that the laundry located in the front and rear portions of the drummay be wet uniformly.

When the water supply valve 720 is opened for the water supply, the drum32 is driven and rotated and the laundry is moved inside the drum 32according to the driving of the drum 32. in this case, the watersupplied via the water supply line 722 connected with the front part ofthe tub 12 may be supplied to the moving laundry located in the frontportion of the drum 32 mostly and the laundry located in the frontportion is wet faster than the laundry located in the rear portion ofthe drum 32.

Until a predetermined time passes after the water supply valve 720 tosupply the water or the water reaches a predetermined water level, thecontrol method according to the second embodiment may not drive the drum32. If the drum 32 is not driven for the predetermined time or until thewater reaches the predetermined water level, the water supplied via thewater supply line 722 may be collected in the lower portion of the tub12 mostly. Here, the predetermined water level may be determined inconsideration of the distance between the tub 12 and the drum. Thepredetermined time may be determined according to the capacities of thetub 12 and the drum 32 and the amount of the laundry.

Especially, the rear portion of the tub 12 in the laundry machinementioned above is installed obliquely downward and a lot of the wateris collected in the rear portion of the tub 12. When the drum 32 isrotated in a predetermined time, the laundry located in the rear portionof the drum 32 may be wet by the water collected in the rear portion ofthe tub 12. When the drum 32 is driven according to the control methodof the second embodiment, the drum driving motion may be embodied as thetumbling motion or scrub motion.

In case the water supply valve 720 is open to supply the water accordingto the second embodiment of the control method, without driving the drum32, the water supply valve 720 may be on-off-controlled. That is, whenthe water supply valve 720 is opened for the water supply, the water mayhave a predetermined pressure because of the water pressure of theexternal water supply source such as a water tap. In this case, thewater supplied via the water supply line 722 may be supplied to thefront portion of the drum by the water pressure, to wet the laundrylocated in the front portion of the drum.

As a result, when the water supply is implemented in the control methodaccording to the second embodiment, the water supply valve 720 may be onand off repeatedly, not opened continuously. The water supply valve 720may be controlled to be on and off for the supplied water to have apredetermined water pressure not to flow into the drum 32 directly.Here, the water pressure not to flow the water into the drum directlymay mean a water pressure enabling the water supplied via the watersupply line 722 to fall down along the drum, tub or door and to becollected in the lower portion of the tub 12, not to be sprayed into thedrum by the water pressure. The water having fallen along the drum, tubor door may be collected in the rear portion of the tub 12 and thedescription after that is similar to the description mentioned above.The repeated description will be omitted accordingly.

In the meanwhile, when the water is supplied in the water supplyingstep, the laundry may be crumbled into a lump and a partial amount ofthe laundry may be wet. Especially, the laundry located in a center ofthe crumbled lump may not be wet and only the laundry located in theouter portion of the crumbled lump. If only the part of the laundry iswet, washing will not be implemented smoothly in the washing cycle, onlyto deteriorate washing efficiency. In case the laundry is crumbled intoa lump, a control method according to a third embodiment configured towet the crumbled laundry uniformly will be described.

The control part opens the water supply valve 720 for the water supplyand it drives the circulation pump 730 to circulate the watersimultaneously. The control part may drive the drum 32 in the filtrationmotion.

That is, the control part may control the drum to be rotated at apredetermined RPM. Here, the predetermined RPM is determined to be a RPMenabling the laundry to be in close contact with the inner wall of thedrum, not dropped by the gravity when the drum is rotated. As a result,the predetermined RPM may be set for a centrifugal force applied to therotating drum to be larger than an acceleration of gravity and thepredetermined RPM may be set lower than an excessive period of thelaundry machine in which resonance is generated (approximately 200 RPMto 35 RPM) if the drum is rotated at the RPM higher than the excessiveperiod, noise and vibration generated by the resonance might beremarkably increased. As a result, the predetermined RPM may be set atapproximately 100 RPM to 170 RPM.

Once the control part rotates the drum 32 at the predetermined RPM, thelaundry is in close contact with the inner wall of the drum 32 becauseof the centrifugal force and the water supplied via the circulation line744 and the water supply line 722 is distributed according to therotation of the drum 32. The distributed water is supplied to the drum32 toward the laundry stuck to the inner wall of the drum 32, such thatthe laundry may be wet uniformly.

In the meanwhile, the control methods configured to wet the laundryuniformly are described, applied to the laundry machine according to thesecond embodiment, and the present invention is not limited thereto. Forexample, the control methods may be applicable to the laundry machineaccording to the first embodiment.

One of the process of the detergent dissolution acceleration and theprocess of wetting the laundry uniformly described above or both of themmay be implemented in the water supplying step. Both of the twoprocesses may be implemented sequentially or repeatedly as well assequentially or reversely, and various combinations of the two processesmay be possible.

Hence, the control part controls the drum to be rotated in the laundrywetting step to wet the laundry. In case the water does not have to beheated, a heating step configured to heat the water by using the heaterprovided in the tub may be implemented. After that, the control partimplements the main washing step by driving the drum 32 and thecirculation pump 730 simultaneously. The drum driving motion in the mainwashing step may be selectable out of the drum driving motions accordingto the course selected by the user. The circulation pump 730 is drivenat a predetermined interval and the water held in the tub 12 iscirculated.

In the meanwhile, a drum inside of the drum type washing machine isvisible from outside via the door 11. The various drum driving motionsmay be implemented in the washing cycle according to the embodiment andthe washing course including the washing cycle. As a result, the usermay see the various drum driving motions implemented in the drum insidedirectly. That is, a soft striking type of washing (tumbling motion), astrong striking type of washing (step motion), soft scrubbing type ofwashing (rolling motion) and a strong scrubbing type of washing (scrubmotion) may be visibly identified. Because of that, the user can sensethat the washing is implemented well and this may create an effect ofimproved user sensibility satisfaction as well as the effect of thesubstantially improved washing efficiency.

Meanwhile, FIG. 8 illustrates a graph showing a relation of mass vs. anatural frequency. It is assumed that, in vibration systems of twolaundry machines, the two laundry machines have mass of m0 and m1respectively and maximum holding laundry amounts are Δm, respectively.Then, the transition regions of the two laundry machines can bedetermined taking Δnf0 and Δnf1 into account, respectively. In thisinstance, amounts of water contained in the laundry will not be takeninto account, for the time being.

In the meantime, referring to FIG. 8, the laundry machine with smallermass ml has a range of the transition region greater than the laundrymachine with greater mass m0. That is, the range of the transitionregion having variation of the laundry amount taken into account becomesthe greater as the mass of the vibration system becomes the smaller.

The ranges of the transition regions will be reviewed on the related artlaundry machine and the laundry machine of the embodiment.

The related art laundry machine has a structure in which vibration istransmitted from the drum to the tub as it is, causing the tub tovibrate. Therefore, in taking the vibration of the related art laundrymachine into account, the tub is indispensible. However, in general, thetub has, not only a weight of its own, but also substantial weights at afront, a rear or a circumferential surface thereof for balancing.Accordingly, the related art laundry machine has great mass of thevibration system.

Opposite to this, in the laundry machine of the embodiment, since thetub, not only has no weight, but also is separated from the drum in viewof a supporting structure, the tub may not be put into account inconsideration of the vibration of the drum. Therefore, the laundrymachine of the embodiment may have relatively small mass of thevibration system.

Then, referring to FIG. 8, the related art laundry machine has mass m0and the laundry machine of the embodiment has mass ml, leading thelaundry machine of the embodiment to have a greater transition region,at the end.

Moreover, if the amounts of water contained in the laundry are takeninto account simply, Δm in FIG. 8 will become greater, making a rangedifference of the transition regions even greater. And, since, in therelated art laundry machine, the water drops into the tub from the drumeven if the water escapes from the laundry as the drum rotates, anamount of water mass reduction come from the spinning is small. Sincethe laundry machine of the embodiment has the tub and the drum separatedfrom each other in view of vibration, the water escaped from the druminfluences the vibration of the drum, instantly. That is, the influenceof a mass change of the water in the laundry is greater in the laundrymachine of the embodiment than the related art laundry machine.

Under above reason, though the related art laundry machine has thetransition region of about 200˜270 rpm, A start RPM of the transientregion of the laundry machine according to this embodiment may besimilar to a start RPM of the transient region of the conventionallaundry machine. An end RPM of the transient region of the laundrymachine according to this embodiment may increase more than a RPMcalculated by adding a value of approximately 30% of the start RPM tothe start RPM. For example, the transient region finishes at an RPMcalculated by adding a value of approximately 80% of the start RPM tothe start RPM. According to this embodiment, the transient region mayinclude a RPM band of approximately 200 to 350 rpm.

In the meantime, by reducing intensity of the vibration of the drum,unbalance may be reduced. For this, even laundry spreading is performedfor spreading the laundry in the drum as far as possible before therotation speed of the drum enters into the transition region.

In a case, a balancer is used, a method may be put into account, inwhich the rotation speed of the drum passes through the transitionregion while movable bodies provided in the balancer are positioned onan opposite side of an unbalance of the laundry. In this instance, it ispreferable that the movable bodies are positioned at exact opposite ofthe unbalance in middle of the transition region.

However, as described above, the transient region of the laundry machineaccording to this embodiment is relatively wide in comparison to that ofthe conventional laundry machine. Because of that, even if the laundryeven-spreading step or ball balancing is implemented in a RPM band lowerthan the transient region, the laundry might be in disorder or balancingmight be failed with the drum speed passing the transient region.

As a result, balancing may be implemented at least one time in thelaundry machine according to this embodiment before and while the drumspeed passing the transient region. Here, the balancing may be definedas rotation of the drum at a constant-speed for a predetermined timeperiod. Such the balancing allows the movable body of the balancer tothe opposite positions of the laundry, only to reduce the unbalanceamount. By extension, the effect of the laundry even-spreading.Eventually, the balancing is implemented while the drum speed passingthe transient region and the noise and vibration generated by theexpansion of the transient region may be prevented.

Here, when the balancing is implemented before the drum speed passingthe transient region, the balancing may be implemented in a differentRPM band from the RPM of the conventional laundry machine. For example,if the transient region starts at 200 RPM, the balancing is implementedin the RPM band lower than approximately 150 RPM. Since the conventionallaundry machine has a relatively less wide transient region, it is notso difficult for the drum speed to pass the transient region even withthe balancing implemented at the RPM lower than approximately 150 RPM.However, the laundry machine according to this embodiment has therelatively wide expanded transient region as described above. if thebalancing is implemented at the such the low RPM like in theconventional laundry machine, the positions of the movable bodies mightbe in disorder by the balancing implemented with the drum speed passingthe transient region. Because of that, the laundry machine according tothis embodiment may increase the balancing RPM in comparison to theconventional balancing RPM, when the balancing is implemented before thedrum speed enters the transient region. That is, if the start RPM of thetransient region is determined, the balancing is implemented in a RPMband higher than a RPM calculated by subtracting a value ofapproximately 25% of the start RPM from the start RPM. For example, thestart RPM of the transient region is approximately 200 RPM, thebalancing may be implemented in a RPM band higher than 150 RPm lowerthan 200 RPM.

Moreover, the unbalance amount may be measured during the balancing.That is, the control method may further include a step to measure theunbalance amount during the balancing and to compare the measuredunbalance amount with an allowable unbalance amount allowing theacceleration of the drum speed. If the measured unbalance amount is lessthan the allowable unbalance amount, the drum speed is accelerated afterthe balancing to be out of the transient region. In contrast, if themeasured unbalance amount is the allowable unbalance amount or more, thelaundry even-spreading step may be re-implemented. in this case, theallowable unbalance amount may be different from an allowable unbalanceamount allowing the initial accelerating.

In addition, vibration characteristics of the laundry machine accordingto the embodiment of the present invention will now be described withreference to FIG. 9.

As the rotation speed of the drum is increased, a region (hereinafter,referred to as “transient vibration region”) where irregular transientvibration with high amplitude occurs is generated. The transientvibration region irregularly occurs with high amplitude before vibrationis transited to a steady-state vibration region (hereinafter, referredto as “steady-state region”), and has vibration characteristicsdetermined if a vibration system (laundry machine) is designed. Thoughthe transient vibration region is different according to the type of thelaundry machine, transient vibration occurs approximately in the rangeof 200 rpm to 270 rpm. It is regarded that transient vibration is causedby resonance. Accordingly, it is necessary to design the balancer byconsidering effective balancing at the transient vibration region.

In the mean time, as described above, in the laundry machine accordingto the embodiment of the present invention, the vibration source, i.e.,the motor and the drum connected with the motor are connected with thetub 12 through the rear gasket 250. Accordingly, vibration occurring inthe drum is little forwarded to the tub, and the drum is supported by adamping means and the suspension unit 180 via a bearing housing 400. Asa result, the tub 12 can directly be fixed to a cabinet 110 without anydamping means.

As a result of studies of the inventor of the present invention,vibration characteristics not observed generally have been found in thelaundry machine according to the present invention. According to thegeneral laundry machine, vibration (displacement) becomes steady afterpassing through the transient vibration region. However, in the laundrymachine according to the embodiment of the present invention, a region(hereinafter, referred to as “irregular vibration”) where vibrationbecomes steady after passing through the transient vibration region andagain becomes great may be generated. For example, if the maximum drumdisplacement or more generated in an RPM band lower than the transientregion or the maximum drum displacement or more of steady state step ina RPM band higher than the transient region is generated, it isdetermined that irregular vibration is generated. Alternatively, if anaverage drum displacement in the transient region, +20% to −20% of theaverage drum displacement in the transient region or ⅓ or more of themaximum drum displacement in the natural frequency of the transientregion are generated, it may be determined that the irregular vibrationis generated.

However, as a result of the studies, irregular vibration has occurred ina RPM band higher than the transient region, for example has occurred ata region (hereinafter, referred to as “irregular vibration region”) inthe range of 350 rpm to 1000 rpm, approximately. Irregular vibration maybe generated due to use of the balancer, the damping system, and therear gasket. Accordingly, in this laundry machine, it is necessary todesign the balancer by considering the irregular vibration region aswell as the transient vibration region.

For example, the balancer is provide with a ball balancer, it ispreferable that the structure of the balancer, i.e., the size of theball, the number of balls, a shape of the race, viscosity of oil, and afilling level of oil are selected by considering the irregular vibrationregion as well as the transient vibration region. When considering thetransient vibration region and/or the irregular vibration region,especially considering the irregular vibration region, the ball balancerhas a greater diameter of 255.8 mm and a smaller diameter of 249.2. Aspace of the race, in which the ball is contained, has a sectional areaof 411.93 mm2. The number of balls is 14 at the front and the rear,respectively, and the ball has a size of 19.05 mm. Silicon based oilsuch as Poly Dimethylsiloxane (PDMS) is used as the oil. Preferably, oilhas viscosity of 300 CS at a room temperature, and has a filling levelof 350 cc.

In addition to the structure of the balancer, in view of control, it ispreferable that the irregular vibration region as well as the transientvibration region is considered. For example, to prevent the irregularvibration, if the irregular vibration region is determined, thebalancing may be implemented at least one time before, while and afterthe drum speed passes the irregular vibration region. Here, if therotation speed of the drum is relatively high, the balancing of thebalancer may not be implemented properly and the balancing may beimplemented with decreasing the rotation speed of the drum. however, ifthe rotation speed of the drum is decreased to be lower than thetransient region to implement the balancing, it has to pass thetransient region again. In decreasing the rotation speed of the drum toimplement the balancing, the decreased rotation speed may be higher thanthe transient region.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A control method of a laundry machine comprising: a water supplyingstep configured to drive a drum in a scrub motion when water is suppliedto a tub.
 2. The control method as claimed in claim 1, wherein acirculating step configured to circulate the water inside the tub tore-supply the water to the tub is implemented at the same time when thewater supplying step starts.
 3. The control method as claimed in claim1, wherein the laundry machine comprises a driving unit comprising ashaft connected to a drum, a bearing housing to rotatably support theshaft, and a motor to rotate the shaft, and a suspension assembly isconnected to the driving unit.
 4. The control method as claimed in claim1, wherein the laundry machine comprises a rear gasket for sealing toprevent washing water from leaking from a space between a driving unitand a tub, and enabling the driving unit movable relative to the tub. 5.The control method as claimed in claim 1, wherein a tub is supportedrigidly more than a drum being supported by a suspension assembly.
 6. Acontrol method of a laundry machine comprising: a washing cyclecomprising at least one water supplying step configured to drive a drumin a predetermined time period after water supply to a tub starts orafter a water level reaches a predetermined value.
 7. The control methodas claimed in claim 6, wherein the tub and the drum provided in thelaundry machine have rear portions which are tilted downward,respectively.
 8. The control method as claimed in claim 6, wherein thetub and the drum provided in the laundry machine have rear portionswhich are tilted downward, respectively.
 9. The control method asclaimed in claim 8, wherein a circulating line configured to circulatethe water is connected to a front portion of the tub.
 10. The controlmethod as claimed in claim 6, wherein a water supply line provided inthe laundry machine is connected to a front portion of the tub, and theon-time of a water supply vale is set to be shorter than the off-time,when the water supply vale is turned on.
 11. The control method asclaimed in claim 10, wherein the on-time is determined to allow watersupplied via the water supply line to have less than a predeterminedwater pressure.
 12. The control method as claimed in claim 11, whereinthe on-time of the water supply valve is determined to allow watersupplied via the water supply line to have a predetermined waterpressure high enough not to be directly supplied to the drum.
 13. Thecontrol method as claimed in claim 1, wherein the laundry machinecomprises a driving unit comprising a shaft connected to a drum, abearing housing to rotatably support the shaft, and a motor to rotatethe shaft, and a suspension assembly is connected to the driving unit.14. The control method as claimed in claim 6, wherein the laundrymachine comprises a rear gasket for sealing to prevent washing waterfrom leaking from a space between a driving unit and a tub, and enablingthe driving unit movable relative to the tub.
 15. The control method asclaimed in claim 6, wherein a tub is supported rigidly more than a drumbeing supported by a suspension assembly.